Pumps are used to transport processed water or fluid systems in various industrial applications. These pumps are driven by electrical motors coupled to the pump. The shaft will extend through a gland or stuffing box to separate the wet environment of the pump from the dry environment of the electrical motor.
Gland packings or stuffing box seals will wear out after time due to the abrasive effects of the rotating shaft and the frictional heat which builds up in the gland or stuffing box itself. Process or quench water is introduced into the gland or stuffing box to act as a lubricant to reduce the frictional wear on the gland or stuffing box. The water not only acts as a lubricant but also flushes away harmful debris and improves the mechanical seals.
A sealed water line is used to deliver the water to the gland or stuffing box. The gland water flow rates and pressure must be controlled in order to maximize the effectiveness of the water.
Various devices are commonly used for controlling flow and pressure. Needle valves, gate or globe valves, ball valves, flow meters and fixed orifice pipe unions are all used for controlling flow and pressure. All of these devices use a sliding or fixed member which can be adjusted to control the limit of flow through the controlled area. These devices are prone to clogging since a very small cross-sectional areas are used to pass the water flow in order to reduce the flow or pressure to the desired levels. These devices are known to plug particularly when upstream filters or strainers are not maintained properly. This problem becomes very critical when raw water is used. During spring run-off, the increased levels of sand and silt in the quench water line results in plugging and ultimately results in seal breakdown and costly downtime.
Further, these devices are not well suited to produce fixed flow rates since the devices are primarily designed for variable flow rates. Different technicians may adjust such device increasing water consumption and sewage costs.
Various devices are known which use a long coil of metal tubing to regulate the flow and pressure of a fluid flow. One such device is disclosed in U.S. Pat. No. 2,120,001. In this device, the flow of beer is regulated using a spiral coil. The device will draw beer directly from the keg which retaining the gas and pressure therein but the flow at the faucet will be substantially atmospheric. Such devices produce a satisfactory result if a loosely wound coil is used.
Problems arise during the manufacture of a flow and pressure reducer using a simple coil. During assembly, the end caps of the housing will compress the coil. However, the compression forces at the transition at the beginning and the end of the coil will cause the tubing to become crimped restricting the flow through the device. This result is highly unsatisfactory as the crimp will affect the amount of flow and pressure reduction which has been carefully and accurately calculated. In such cases, the device will have an unpredictable amount of flow and pressure reduction resulting in a high incidence of defective devices.